Centrifugal molds and method of forming hollow articles

Claim 1

A HOLLOW MOLD FOR CENTRIFUGAL CASTING OF A HOLLOW GLASS ARTICLE, SAID MOLD BEING OPEN AT ITS UPPER END AND HAVING UPWARDLY-FLARED INNER WALL SURFACES PROVIDING A HOLLOW GENERALLY FUNNEL-SHAPED MOLD CAVITY, A DEPENDING CIRCUMFERENTIAL LEDGE EXTENDING HORIZONTALLY OUTWARDLY FROM THE UPPER EDGE OF SAID WALL SURFACES, A CONVERGENT EXTERIORLY-PROJECTING CONTINUOUS ANNULAR RIB DISPOSED AT THE INTERSECTION OF SAID LEDGE AND THE UPPER EDGE OF SAID WALL SURFACES, SAID RIB HAVING A KNIFE-LIKE EDGE ADAPTED TO FORMING A COMPLEMENTAL ANNULAR GROOVE ALONG A DESIRED LINE OF SEPARATION ADJACENT A REGION OF SUBSTANTIALLY MAXIMUM CROSS-SECTIONAL DIMENSIONS OF SAID HOLLOW ARTICLE CONTIGUOUS WITH ITS FORMATION BY CENTRIFUGAL CASTING.

Claim 3

THE METHOD OF FORMING A HOLLOW GLASS ARTICLE HAVING UPWARDLY FLARED SIDEWALLS, WHICH METHOD COMPRISES THE STEPS OF ENTERING A CHARGE OF MOLTEN GLASS INTO AN OPEN-ENDED MOLD HAVING UPWARDLY FLARING SIDEWALLS EXTENDING TOWARD THE OPEN END OF THE MOLD, SAID MOLD HAVING AN OUTWARDLY AND UPWARDLY PROJECTING RECTANGULARLYSHAPED ANNULAR LEDGE AND FLANGE PORTION EXTENDING AROUND ITS OPEN END, RAPIDLY ROTATING THE MOLD ABOUT ITS VERTICAL AXIS AND THEREBY SPREADING THE GLASS AND CAUSING IT TO TRAVEL UP THE SIDEWALLS OF THE MOLD THUS FORMING A GENERALLY FRUSTO-PYRAMIDAL SHAPED OPEN-ENDED HOLLOW MOLDED ARTICLE FLOWING AT LEAST A MINOR PORTION OF THE GLASS HORIZONTALLY AND RADIALLY OVER A SHARPLY-POINTED UPPER EDGE OF THE MOLD INTO THE OUTWARDLY-PROJECTING ANNULAR LEDGE DURING SUCH ROTATION TO FORM AN UPPER RIM OF SAID ARTICLE SIMULTANEOUSLY FORMING AN ANNULAR GROOVE HAVING A SHAPLY DEFINED RE-ENTRANT ANGLE IN THE MOLDED UNDERSIDE SURFACE OF THE UPPER RIM PORTION, DECELERATING AND STOPPING THE ROTATION OF THE MOLD, AND COOLING THE MOLDED GLASS ARTICLE AT SUCH A RATE SO AS TO ESTABLISH THERMALLY INDUCED STRESSES IN THE GLASS ABOVE THE ANNULAR GROOVE OF SUCH MAGNITUDE THAT SERVEANCE OF THE ARTICLE OCCURS ALONG SUCH GROOVE UPON SOLIDIFICATION OF THE GLASS.

Claim 4

THE METHOD OF FORMING A HOLLOW GLASS ARTICLE HAVING UPWARDLY FLARED SIDEWALLS, WHICH METHOD COMPRISES THE STEPS OF ENTERING A CHARGE OF MOLTEN GLASS INTO AN OPEN-ENDED MOLD HAVING UPWARDLY FLARING SIDEWALLS EXTENDING TOWARD THE OPEN END OF THE MOLD, SAID MOLD HAVING AN OUTWARDLY AND UPWARDLY PROJECTING RECTANGULARLYSHAPED ANNULAR LEDGE AND FLANGE PORTION EXTENDING AROUND ITS OPEN END, RAPIDLY ROTATING THE MOLD ABOUT ITS VERTICAL AXIS AND THEREBY SPREADING THE GLASS AND CAUSING IT TO TRAVEL UP THE SIDEWALLS OF THE MOLD THUS FORMING A GENERALLY FRUSTO-PYRAMIDAL SHAPED OPEN-ENDED HOLLOW MOLDED ARTICLE FLOWING AT LEAST A MINOR PORTION OF THE GLASS HORIZONTALLY AND RADIALLY OVER A SHARPLY-POINTED UPPER EDGE OF THE MOLD INTO THE OUTWARDLY-PROJECTING ANNULAR LEDGE DURING SUCH ROTATION TO FORM AN UPPER RIM OF SAID ARTICLE SIMULTANEOUSLY FORMING AN ANNULAR GROOVE HAVING A SHAPLY DEFINED RE-ENTRANT ANGLE IN THE MOLDED UNDERSIDE SURFACE OF THE UPPER RIM PORTION, DECELERATING AND STOPPING THE ROTATION OF THE MOLD, AND COOLING THE MOLDED GLASS ARTICLE AT SUCH A RATE SO AS TO ESTABLISH THERMALLY INDUCED STRESSES IN THE GLASS ABOVE THE ANNULAR GROOVE OF SUCH MAGNITUDE THAT SERVEANCE OF THE ARTICLE OCCURS ALONG SUCH GROOVE UPON SOLIDIFICATION OF THE GLASS.